1. Field of the Invention
The invention relates to an operating arrangement for movable parts on motor vehicles, especially for trunk lids, folding tops and the like, which has at least one hydraulic cylinder with a piston rod as the driving means to act on the movable part either directly or indirectly, for example by a hinge, and at least one pump arrangement, including tank, motor, and similar items connected to the hydraulic cylinder.
2. The Prior Art
With hydraulic working cylinders it is customary to arrange control valves, non-return valves and safety valves or the like on the cylinder itself as needed, while the pump arrangement, including the tank which supplies pressurized hydraulic fluid to the cylinder, is placed a distance away from the cylinder and is connected to it by pressure pipes. Thus, for example, with operating arrangements for movable parts on motor vehicles, such as trunk lids, engine hoods and the like, the hydraulic cylinders as the driving means are mounted in the immediate vicinity of these parts to be directly linked to them in part, while the pump together with the motor, valve arrangements, tank, etc., can also be mounted at a distance, depending on the available space, e.g., on a mounting plate with a vibration absorber.
The disadvantages of such configurations include, among other things, the long connecting lines required because of the pressure drop occurring in them, the danger of damage, the space required for installation, and also the cost of construction and manufacturing.
The design according to U.S. Pat. No. 4,551,973 is much more compact. This invention concerns a hydraulic drive unit wherein the hydraulic cylinder and the motor-pump unit are mounted on a common base. Because of the fixed size of the common base, however, the possibilities of adapting the unit to different areas of use are very limited, and this makes maintenance and replacement of individual parts very difficult.
The object of the present invention is therefore to provide a compact operating arrangement which can be adapted quickly and easily to the given requirements and can also be serviced easily or repaired by replacing individual parts.